Half of holidaymakers will return home from trips abroad to a mobile phone bill of £150 because they do not understand roaming costs.

A fifth of travellers do not check how much their mobile phone provider charges when they use their phone abroad, according to research by comparison website uSwitch.com. Furthermore, seven in ten consumers leave their phone switched on all the time, despite never intending to use it, leave themselves open to high overseas charges.

This is because the minute a mobile is switched on abroad, it will register onto a local network, meaning customers will be charged international rates to receive calls or even having a voicemail message.

Brits are also being caught out by their need to keep in touch with those back at home while on holiday. A third admit they will use their phone abroad to check emails and while a quarter intend to use Twitter or Facebook on their phone.

Ernest Doku, technology expert at uSwitch.com, said: "Contacting your mobile phone network should be high on every mobile user's holiday checklist, alongside packing your passport and sun cream. If people don't want to add to their post-holiday blues by coming home to a 'bill shock', they need to take control."